Hi Pedro,
Teams often create and estimate tasks at once before activating the sprint, during the sprint planning meeting. In this case, iceScrum can compute the « ideal » median line: a simple downward line from the initial estimate to 0. The first point captures the total estimate when the sprint is activated. By contrast, the remaining time first point is the total remaining time at the end of the day of the sprint activation.
The median line makes sense only if the total task estimate is intended to decrease regularly during the sprint from this initial value. If tasks are not estimated all at once then iceScrum has no way to guess what should be the ideal curve and the median line becomes irrelevant so you can hide it by clicking on the « Median line » label in the caption. The line will not be displayed at all if there is not task estimate when the sprint is activated.
We recommend that either all tasks are estimated before sprint activation (of course the team may forget one or two tasks and create / estimate them later on) or no task is estimated before sprint activation, thus ensuring that the line is displayed only when it is meaningful.
Nicolas
